Thread tensioning device for sewing machines

ABSTRACT

A needle thread tensioning mechanism for a sewing machine which is arranged in the removable top cover of a sewing machine bracket arm. A diminutive thread engaging head and operator influenced tension adjusting member protrude exteriorly of the top cover, while the mechanisms for influencing the tension imposed upon the thread and a tension releasing means are carried inside the top cover.

United States Patent 15] 3,667,414 Illes et a1. 5] June 6, 1972 [54] THREAD TENSIONING DEVICE FOR 2,965,058 12/1960 Herbst et a1. ..112/2s4 SEWING MACHINES 3,366,083 1/1968 Ketterer et a] ....1 12/254 ,6 1 5 b rt [72] Inventors: Stephen J. Illes, Summit, N.J.; Salvatore A. 2 O9 772 9/ 9 2 Casas R0 6 l 2/254 D Staten Island Primary Examiner-Jordan Franklin [73] Assignee: The Singer Company, New York, NY. Assistant Examiner-George H. Krizmanich Attorney-Marshall J. Breen, Chester A. Williams, Jr. and

l [22] F1 ed Sept 25, 1970 Robert E. Smith [21] App1.No.: 75,430

[57] ABSTRACT A needle thread tensioning mechanism for a ewing machine [51] I "Dosh 47/00 which is arranged in the removable top cover of a sewing [58] Field Of Search .11 [2/254, 255; 242/150 inachine bracket arm A diminutive thread engaging h and operator influenced tension adjusting member protrude ex- [56] References C'ted teriorly of the top cover, while the mechanisms for influencing UNITED STATES PATENTS the tension imposed upon the thread and a tension releasing means are carried inside the top cover. 3,190,249 6/1965 Gegauf ..112/254 2,955,775 10/ 1 960 Johnson ..242/ 150 5 Claims, 7 Drawing Figures PATENTED 6 I972 SHEET 10F 3 INVENTORQ J Illes Stephen BY Salvatore A. D'Orio ATTORNEY PATENTEDJUH 6 m2 ,3. 667. 414

sum 2 or a usJ ' INVENTORE) L phen J. Illes BY Salvatore A. D'Orio WITNESS? WM .620

(I A TORNEY THREAD TENSIONING DEVICE FOR SEWING MAiTI-[INES BACKGROUND OF THE INVENTION It is conventional to direct the needle thread of a sewing machine from a source of supply first to a thread tensioning device, then to the action of a take-up mechanism and finally to the needle. Where the take-up mechanism is adjacent to and associated with the needle bar of the sewing machine, the thread tensioning device is usually arranged on the sewing machine bracket arm beneath the take-up mechanism, thus providing the most direct thread path from the tensioning device to the take-up mechanism.

Certain disadvantages stem from this conventional arrangement in that the thread tensioning device is located where it blocks the operators view of the fabrics being stitched, and the thread tensioning device together with necessary supporting and operating structure such as tension releasing mechanism occupy critical space in the sewing head of the machine which is crowded with other mechanisms.

SUMMARY OF THE INVENTION It is an object of this invention to provide a needle thread tensioning device for a sewing machine constructedand arranged so as not to detract from the operator's view of the work being stitched and so as not to compete for space occupied by other mechanisms within the sewing machine.

This object of the present invention is attained by a needle thread tensioning device which is located in the removable top cover for a sewing machine. This location, unoccupied by any other operating mechanism of the sewing machine, places the exposed portions of the thread tensioning device beyond the line of sight of an operator toward the work being sewn.

DESCRIPTION OF THE DRAWINGS With the above and additional objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 is a perspective view of the thread tensioning device of this invention with the removable top cover of the sewing machine shown in phantom lines,

FIG. 2 is an exploded perspective view of the thread tensioning head of the device of this invention,

FIG. 3 is an enlarged bottom plan view of a portion of the sewing machine top cover with the thread tensioning head illustrated in cross section,

FIG. 4 is a front elevational view of a sewing machine having this invention applied thereto, and with portions of the machine frame broken away to illustrate the tension releasing mechanism,

FIG. 5 is a cross sectional view taken substantially along line 55 of FIG. 3,

FIG. 6 is a cross sectional view taken substantially along line 6-6 ofFlG. 3 and;

FIG. 7 is a cross sectional view taken substantially along line 7-7 of FIG. 3.

Referring to FIG. 4, this invention is illustrated as applied to a sewing machine having a bed 11 and a bracket arm 12 overhanging the bed and terminating in a sewing head '13. Preferably the bracket arm and sewing head are hollow and are provided with an opening at the top adapted to be closed by a top cover plate 14 which is removable and may be fastened to the bracket arm by any suitable means. A reciprocatory needle bar 15 is joumaled in the sewing head 13 and has a thread carrying needle 16 secured at its lower end by a clamp device 17. The needle bar 15 and a needle thread take-up arm 18 having a thread eye 19 closely adjacent thereto are imparted reciprocatory movements in concert by a drive mechanism (not shown) in the bracket arm.

The needle thread tensioning device of this invention is carried by the removable top cover 14 of the sewing machine frame. The needle thread tensioning device includes a thread engaging head 20 which extends exteriorly of the top cover closely adjacent the path of movement of the take-up arm 13. Also projecting exteriorly of the top cover 14 alongside the thread engaging head 20 is an operator influenced tension adjusting dial 2] which, as will be described hereinbelow, serves to regulate the tension which is imparted to the thread by the thread engaging head. As shown in FIG. 4, a needle thread N is directed from a supply spool (not shown) to the thread engaging head 20 and to the influence of the elements thereof which will be described in greater detail below, thence downwardly about a thread guiding post 22 which is set into the sewing head and may be formed with a thread detaining skirt 23. The thread guiding post is arranged beneath the path of motion of the take-up arm to the eyelet 19 of which the thread is directed from the thread guiding post. From the takeup arm the thread is directed downwardly to the sewing machine needle 16. Portions of the sewing head, the top cover 14, and portions of an end cover plate 25 have been broken away in FIG. 4 along with portions of the needle bar 15 and driving mechanism of the sewing machine in order to expose a presser bar 26 which is carried in the sewing head parallel to the needle bar. A work engaging presser foot 27 is secured to the lower extremity of the presser bar as by a clamp screw 28 and a downward biasing force may be applied to the presser bar by a plunger 29 slidable in an axial bore in the presser bar and constraining a spring (not shown) therein. A rotary cam 30 pivoted in the sewing head serves to regulate the downward pressure exerted by the presser foot. Secured to the presser bar 26 as by a set screw 31 within the sewing head 13 is a block 32. An operator influenced presser lifter lever pivoted on the sewing head 13 includes a cam portion 36 beneath the block 32 which may raise and lower the presser foot. A vertical rod 33 with a reduced upper extremity 34 is constrained by a clip 37 in a clearance bore 38 in a web 39 of the bracket arm and extends downwardly into engagement with the cam portion 36 of the presser lifting lever to serve for releasing the tension which is applied to the needle thread by the thread engaging head whenever the presser lifting lever is operated.

Referring particularly to FIG. 3, which illustrates the thread engaging head in cross section, and to FIGS. 1 and 2 which illustrate the assemblied and exploded views of the thread engaging head in perspective, the details of construction of the thread engaging head will be described. A central stud 40 is provided 'which is formed at one end with a transverse slot 41 and with external threads 42. Between'its extremities, the stud 40 is formed with an annular flange 43 and an axial bore 44 is provided in the stud extending from the transverse slot 41 to the opposite extremity of the stud. A sleeve 45 is secured as by a press fit on the stud at the opposite side of the flange from the transverse slot and serves to confine against the flange 43 a thread guiding bracket 46. The thread guiding bracket is formed with a rotation restraining finger 47 which, as shown in FIG. 4, fits into a notch in the top cover 14. At each side of the rotation restraining finger the thread guiding bracket is formed with contiguous oppositely directed thread guiding notches 48 and 49 which accommodate the incoming and outgoing limbs respectively of a loop of thread which is directed to the thread engaging head.

Carried on the transversely slotted extremity of the stud 40 against the flange 43 are three thread frictioning washers 50 at the opposite side of which a disk 51 is provided having an aperture 52 accommodating the stud and fingers 53 which extend into the transverse slot 41. A rod 54 slidable axially in the bore 44 of the stud is formed with a head 55 larger than the space between the fingers 53 on the disk 51. A force, therefore, applied lengthwise along the axially shiftable rod 54 will impart pressure on the washers 50. Threadedly engaging the threads 42 on the stud 40 is a cupshaped member 56 which serves to constrain against the disk 51. A light coil spring 57 which serves to impart a small force to the washers 50 even when the main thread tensioning force exerted through the rod 54 is completely removed therefrom. By turning the cupshaped member on the threads 42 a regulation of the pressure exerted by the light spring member may be effected. The cupshaped member 56 also provides a reception seat for a coil 58 at one extremity of a spring wire check spring 60. A plurality of coils 61 formed at the other extremity of the check spring are accommodated on the sleeve 45, and the inturned extremity 62 of the check spring coils 61 extends into a transverse slot 63 formed in the sleeve 45 to anchor the check spring.

A washer 65 is provided on the stud 40 against the cupshaped member 56 and a cover member 66 is secured against the washer 56 by a threaded nut 67 engaging the threads 42 on the stud. The cover member 66 is formed with a skirt 68 which together with a skirt 69 formed on the thread guiding bracket 46 shroud the thread frictioning washers 50. A notch 70 formed in the skirt 68 of the cover member 66 provides space for egress of the check spring 60.

Referring to FIG. 3, the top cover 14 is formed with a recess providing a reception seat into which the stud 40 is accommodated and locked in place by a set screw 81. The recess 80 is preferably large enough to accommodate the sleeve 45 and the coils 61 of the check spring.

The organization of the mechanism for imparting and regulating pressure between the thread frictioning washers 50 so as to impart tension to a sewing thread is best illustrated in FIGS. 1 and 3. This tension influencing mechanism is carried interiorly of the top cover 14 above the bracket am 12 and in a space which is not ordinarily occupied by any operating mechanism of a conventional sewing machine. Secured by a fastening screw beneath the cover plate is a bracket 91 formed with a tang 92 which may engage a projection 93 formed beneath the top cover to prevent turning movement of the bracket 91. Threaded'in a pair of spaced arms 94 and 95 on the bracket 91 is a mandrel 96 formed with a plain cylindrical extremity 97. A coil spring 98 which is constrained on the plain cylindrical extremity between abutment washers 99 and 100 thereon provides the spring pressure which will be applied by the mechanism now being described to bias the thread frictioning washers together.

The force of the spring 98 is transmitted to the rod 54 by a rigid lever preferably having a U-shaped cross section as best illustrated in FIG. 7. The lever 110 is formed with an aperture 111 embracing the plain cylindrical extremity 97 of the mandrel 96 and a pair of projections 112 may be struck out from the lever 110 to engage the washer 100 substantially along the center line of the mandrel 96. The lever 110 at the opposite extremity is formed with an aperture 113 through which the rod 54 extends. As best illustrated in FIG. 5, a head 114 formed on the rod 54 is smaller than the main portion of the aperture 113 and can be inserted therethrough, however, a narrow lateral portion 115 of the aperture 113 is smaller than the head 114 of the rod and serves to lock the rod 54 to the lever when the head 114 is releasably detained therein by a spring clip 116 snapped into position across the main portion of the aperture 1 13. The spring clip, as shown in FIG. 6, preferably extends through openings 117 therefor in the lever 110 and includes a spring clip portion 118 folded back upon itself yieldingly to engage of the lever 110 to retain the spring clip 116 in place.

A fulcrum is provided for the lever 1 10 by means of a pair of laterally extending fulcrum fingers or projections 120 carried by a slide member 121 which preferably includes a U-shaped portion nested within the U-shaped section of the lever 110 as illustrated in FIG. 7. The slide member 121 is constrained for a substantially rectilinear movement by a lengthwise guide slot 122 which embraces a shouldered pivot pin 123 which is screw threaded into the top cover 14 and by a guide abutment 124 which is formed interiorly of the top cover 14 at the opposite side of the slide member 121 from the lever 110. The tension regulating dial segment 21 is journaled for turning movement on the pivot pin 123 and projects outwardly of the top cover through a slot 125 therein. A crank pin 126 projecting from the dial segment 21 is embraced in a slot 127 formed in the slide member 121 substantially at right angles to the guide slot 122. By this arrangement turning of the dial segment 21 will, by way of the crank pin 126, shift the slide member 121 to move the fulcrum projections 120 along the lever 110. The position of the parts as shown in FIG. 3 illustrates the fulcrum projections located directly opposite the axis of the mandrel 96 so that the pressure of the spring 98 is completely removed from the rod 54 and only the light spring pressure of the spring 57 will be applied to the thread engaging washers 50. As the fulcrum projections 120 are moved toward the rod 54 along the lever 110, the lever arms will be changed to impart an increasingly greater component of the pressure of the spring to the rod 54. The threaded mandrel 96 may be turned in the spaced arms 94 and 95 of the bracket 91 to regulate the pressure of the spring 98 which will vary the entire range of pressure settings applied to the thread by the thread engaging head.

The pressure of the spring 98 may be removed from the thread engaging washers 50 whenever desired by a tension release lever 130 which is fulcrumed on a rivet 131 secured into a bracket 132 secured beneath the top cover 14 by a fastening screw 133. The bracket is further stabilized beneath the top cover by a slot 134 therein which embraces a downward projection 135 from the top cover. An offset lever arm 136 on the tension release lever 130 overlies the reduced upper extremity 34 of the vertical rod 33 which is operated by the sewing machine presser bar lifter. A lever arm 137 disposed adjacent the spring force transmitting lever 110 serves when the presser foot is lifted to shift the lever 110 toward the thread engaging head 20 and thus to remove the pressure of the spring 98 from the thread engaging disks 50.

Having thus set forth the nature of this invention, what is claimed herein is:

1. A sewing machine having a frame including a work supporting bed and a hollow upwardly open bracket arm overhanging said bed, an endwise reciprocatory thread carrying needle, and a needle thread take-up mechanism carried in said bracket arm, a needle thread tensioning device comprising a needle thread engaging means including a pair of opposed thread engaging discs carried on a supporting stud for applying frictional resistance to movement of a thread between said discs, a spring, a lever for applying force from said spring to bias said thread engaging discs together, a shiftable fulcrum in said lever, an operator influenced tension regulating member connected to said shiftable fulcrum, a common supporting member for said needle thread engaging means, said spring, said lever, and said tension regulating member, said common supporting member being accommodated on said sewing machine frame so as to position said needle thread tensioning device over said upwardly open bracket arm, a thread guide carried on said bracket arm beneath said thread tensioning device for directing thread from said thread tensioning device to said needle thread take-up mechanism, and a thread guiding element carried on the supporting stud for said thread engaging discs, said thread guiding element being formed with contiguous oppositely directed thread guiding notches, one for each of the limbs of a loop of thread which is directed between said pair of thread engaging discs.

2. A sewing machine thread tension device comprising a thread engaging head including opposed thread engaging disks and an axially shiftable rod for pressing said thread engaging disks together, a reception seat formed on said sewing machine for accommodating said thread engaging head thereon, and means for applying a selectively variable force along said axially shiftable rod comprising an abutment mandrel carried on said sewing machine substantially parallel to said rod, a rigid lever sustained on said mandrel and on said rod, spring means constrained on said mandrel and acting against said rigid lever, a tension adjusting dial journaled on a pivot pin fixed on said sewing machine in spaced relation to both said mandrel and said rod, a slide member having an elongate slot embracing said adjusting dial pivot pin, a fulcrum projection on said slide member constrained to move along said rigid lever, and crank means operatively connecting said tension adjusting dial and said slide member.

3. A sewing machine thread tension device as set forth in claim 2 in which said rigid lever is formed with a U shaped transverse cross sectional configuration, and in which at least a portion of said slide member is also formed with a slightly narrower U shaped transverse cross sectional configuration, in which the limbs of the narrower U shaped slide member portion extend between the limbs of the wider U" shaped rigid lever, and in which the fulcrum projection on the slide member extends from a limb of the U" shaped cross sectional configuration thereof.

4. A sewing machine thread tension device as set forth in claim 2 in which said tension adjusting dial is located at the opposite side of said mandrel from said thread engaging head, and in which said dial, said mandrel and said axially shiftable rod are located in substantially coplanar relationship.

5. A sewing machine thread tension device as set forth in claim 2 in which for releasing the thread tension when a sewing machine presser foot is raised, a tension releasing lever operatively connected with the presser foot is fulcrumed on said sewing machine and arranged for engagement with said rigid lever. 

1. A sewing machine having a frame including a work supporting bed and a hollow upwardly open bracket arm overhanging said bed, an endwise reciprocatory thread carrying needle, and a needle thread take-up mechanism carried in said bracket arm, a needle thread tensioning device comprising a needle thread engaging means including a pair of opposed thread engaging discs carried on a supporting stud for applying frictional resistance to movement of a thread between said discs, a spring, a lever for applying force from said spring to bias said thread engaging discs together, a shiftable fulcrum in said lever, an operator influenced tension regulating member conNected to said shiftable fulcrum, a common supporting member for said needle thread engaging means, said spring, said lever, and said tension regulating member, said common supporting member being accommodated on said sewing machine frame so as to position said needle thread tensioning device over said upwardly open bracket arm, a thread guide carried on said bracket arm beneath said thread tensioning device for directing thread from said thread tensioning device to said needle thread take-up mechanism, and a thread guiding element carried on the supporting stud for said thread engaging discs, said thread guiding element being formed with contiguous oppositely directed thread guiding notches, one for each of the limbs of a loop of thread which is directed between said pair of thread engaging discs.
 2. A sewing machine thread tension device comprising a thread engaging head including opposed thread engaging disks and an axially shiftable rod for pressing said thread engaging disks together, a reception seat formed on said sewing machine for accommodating said thread engaging head thereon, and means for applying a selectively variable force along said axially shiftable rod comprising an abutment mandrel carried on said sewing machine substantially parallel to said rod, a rigid lever sustained on said mandrel and on said rod, spring means constrained on said mandrel and acting against said rigid lever, a tension adjusting dial journaled on a pivot pin fixed on said sewing machine in spaced relation to both said mandrel and said rod, a slide member having an elongate slot embracing said adjusting dial pivot pin, a fulcrum projection on said slide member constrained to move along said rigid lever, and crank means operatively connecting said tension adjusting dial and said slide member.
 3. A sewing machine thread tension device as set forth in claim 2 in which said rigid lever is formed with a ''''U'''' shaped transverse cross sectional configuration, and in which at least a portion of said slide member is also formed with a slightly narrower ''''U'''' shaped transverse cross sectional configuration, in which the limbs of the narrower ''''U'''' shaped slide member portion extend between the limbs of the wider ''''U'''' shaped rigid lever, and in which the fulcrum projection on the slide member extends from a limb of the ''''U'''' shaped cross sectional configuration thereof.
 4. A sewing machine thread tension device as set forth in claim 2 in which said tension adjusting dial is located at the opposite side of said mandrel from said thread engaging head, and in which said dial, said mandrel and said axially shiftable rod are located in substantially coplanar relationship.
 5. A sewing machine thread tension device as set forth in claim 2 in which for releasing the thread tension when a sewing machine presser foot is raised, a tension releasing lever operatively connected with the presser foot is fulcrumed on said sewing machine and arranged for engagement with said rigid lever. 